1. Field of the Invention
The present invention relates to indication of offset values of a cutting tool in a control apparatus which is employed in a cutting machine (specifically an NC lathe or machining center) for performing various cutting according to numerical control.
Particularly, the present invention relates to the control apparatus for the cutting machine in which a turret turns around a B-axis so that cutting process can be conducted at an arbitrary position (capable of indexing at the arbitrary position). Further, the present invention relates to the control apparatus for the cutting machine in which the cutting tool can rotate around the tool axis.
2. Description of the Related Art
(1) In a conventional control apparatus for the cutting machine based on the numerical control, an offset value of a cutting edge of the cutting tool has been indicated, and numerical values for conducting the cutting have been inputted referring to the values. There have been some cutting machines such as the NC lathe and machining center, in which the cutting tool turns around the B-axis. Here, the B-axis is a reference axis regulated by JIS which means an axis perpendicular to both the X-axis and Z-axis of the turret 1 as shown in FIG. 1.
(2) There have been heretofore those control apparatuses in which the offset values are indicated on the bases of coordinate axes relative to the turret, when the turret has turned with respect to the B-axis. For example, in the case where the offset values of the cutting tool have been already determined, the same offset values are indicated at any positions where the turret has turned. In the case where the offset values are (X100, Z25) for example, even though the turret has turned by 90 degree, the offset values have been indicated as (X100, Z25).
In this case, an operator must calculate for himself the offset values according to the position after the turn, and input the numerical values based on the calculated values. This has been a heavy task to the operator, and also there has been a risk of miscalculation.
Particularly, because the X-axis offset value is indicated by diameter, when the turret has turned by 90 degree, the offset value must be twice as much as the Z-axis value and a half of the X-axis value, and the calculation has been annoying. In the case where the turning angle is 40 degree or so, it has been impossible to convert the offset values by mental arithmetic.
(3) Meanwhile, there is Japanese Publication No. JP-A-2000-141164 of unexamined Patent Application which relates to a cutting machine in which the turret can turn around the B-axis and tool compensation values (the offset values) of a cutting edge of the tool are not indicated relative to the turret. However, in this patent application, the tool compensation values corresponding to predetermined turning angles, such as the turns of the turret by every 90 degree, are indicated. Therefore, in the art disclosed in this patent application, the tool compensation values (the offset values) when the turret has turned to arbitrary angles cannot be indicated. Moreover, there has been a problem that if the tool compensation values at every turning angle are to be stored, it will cause an overload of a memory section in the control apparatus.
(4) Further, the above-described problems have existed also, when the cutting tool is rotated around the tool axis.
In view of the above, it is an object of the invention to provide a control apparatus for a cutting machine having a turret which can turn to arbitrary positions, in which offset values on coordinates relative to the cutting machine are indicated, regardless of the position of the turret, and an operator need not calculate the offset values in the cutting process.
It is another object of the invention that the offset values with respect to arbitrary turning angles of the turret can be indicated, while reducing load on a memory section in the control apparatus.
It is a further object of the invention to make it unnecessary to convert the offset values of a cutting edge of the tool after rotation, even in a control apparatus for a cutting machine which can rotate to an arbitrary position relative to a tool axis.
(1) This invention relates to a control apparatus for a cutting machine adapted to conduct numerical control and having a turret 1 which can be turned to arbitrary positions, characterized in that an X-axis offset value (xcex94X) and a Z-axis offset value (xcex94Z) of a cutting edge 3 of a cutting tool when the turret 1 has been turned to an arbitrary angle are converted to values on coordinates relative to the cutting machine, and indicated.
Here, the X-axis offset value (xcex94X) and the Z-axis offset value (xcex94Z) are defined as values for compensating a difference between a position of the cutting edge of the tool assumed on a prepared cutting program and an actual position of the cutting edge, when they are different from each other. Specifically, on coordinates defined by two axes (the X-axis and the Z-axis) perpendicular to each other concerning the positions of the cutting edge of the tool, the value twice as much as the X-axis value (indication by diameter) is referred to as xe2x80x9cthe X-axis offset valuexe2x80x9d, and the Z-axis value is referred to as xe2x80x9cthe Z-axis offset valuexe2x80x9d.
In the conventional cutting machine, the same offset values have been indicated even when the turret 1 has turned around the B-axis. This is because the offset values relative to the turret 1 have been indicated. On the other hand, in this invention, the offset values are not relative to the turret 1, but always indicated as points on the coordinates relative to the cutting machine, at any position where the turret 1 has turned. This facilitates calculation of compensation values to be inputted in the cutting process. For example, in an embodiment as shown in FIGS. 1 to 3, an initial position is set at a position of xe2x88x9290 degree of the turret 1 in FIG. 1, and the offset values after the turret 1 has turned are indicated on the basis of this coordinate.
Also in this invention, at every turn of the turret 1, the offset values are converted according to its turning angle (xcex1) and indicated. Accordingly, the memory section of the control apparatus need not store the offset values at every turning angle, and thus, the load with respect to a capacity for memory will be decreased.
(2) One of desirable embodiments of the invention is the above described control apparatus, characterized in that wear compensation values (xcex94Xt, xcex94Zt) are indicated in relation to the X-axis offset value (xcex94X) and the Z-axis offset value (xcex94Z). Further, this control apparatus is preferably in such a form that the inputted wear compensation values (xcex94Xt, xcex94Zt) may be indicated in order of the input.
An ordinary cutting process is not completed by a single cutting, but several cuttings must be conducted. This is done so as to avoid cutting too much when the cutting is conducted at a time, and so as to compensate for wear of the cutting edge of the tool.
When such several cuttings are conducted, the operator measures sizes of a workpiece to be cut after the cutting process, and further cuts a portion exceeding a preset value by inputting the wear compensation values. In this case, the wear compensation values are inputted with reference to the X-axis offset value (xcex94X) and the Z-axis offset value (xcex94Z) which are indicated. However, the wear compensation values to be inputted at a second and successive cuttings must be set with reference to the wear compensation values which have been inputted at a previous cutting, so that a further cutting may be conducted in addition to the inputted values.
For example, in case where the offset value is (X 100.0) and the wear compensation value at a first cutting is (xe2x88x920.1) in cutting an outer periphery, the compensation value at the second cutting must be smaller than (xe2x88x920.1). If the compensation value of (xe2x88x920.05) is inputted at the second cutting, the cutting will not be conducted. In this manner, not only the offset value but also the wear compensation value at the previous cutting has a significant meaning when inputting the wear compensation value.
Accordingly, this invention is able to provide the operator with guidelines for the wear compensation values by inputting not only the offset values on the X-axis and the Z-axis, but the wear compensation values (xcex94Xt, xcex94Zt) with reference to the offset values. In addition, by providing means for indicating the inputted wear compensation values in order, the operator can see a history of the wear compensation values in the past, and can easily set the next wear compensation values.
(3) This invention also relates to the above described control apparatus, which can be implemented in such a manner that when the turret 1 has been turned to a turning angle (xcex1), an X-axis value of the tool (L2), a Z-axis value of the tool (L1), an X-axis value of the turret (L4) and a Z-axis value of the turret (L3) are converted according to the following equations to calculate the aforesaid X-axis offset value (xcex94X) and the Z-axis offset value (xcex94Z).
xcex94X=(xcex94Azxc2x7cos xcex1xe2x88x92xcex94Axxc2x7sin xcex1)xc3x972xe2x80x83xe2x80x83(Equation 1)
xcex94Ax=L2+L4
xcex94Az=L1+L3
xcex94Z=xe2x88x92xcex94Azxc2x7sin xcex1xe2x88x92xcex94Axxc2x7cos xcex1xe2x80x83xe2x80x83(Equation 2)
(xcex1: turning angle of the turret 1 relative to the B-axis. A vertically downward direction of the X-axis in FIG. 1 is set to be 0 degree)
This invention is characterized in that any position to which the turret 1 has turned is converted to points on the coordinates relative to the cutting machine, and indicated. There is no restriction in the equations for the conversion. In an embodiment in which the size L3 or L4 of the turret 1 varies according to the turn of the turret 1, in case where the size L1 or L2 of the tool varies, and in case where an axis of the turn is not perpendicular to the X-axis and the Z-axis, it is possible to perform the conversion by employing appropriate conversion equations taking those variations into consideration.
The above described equations for the conversion are employed in one of the embodiments according to this invention, and the equations for the conversion when the turret 1 simply turns around the B-axis are shown in FIGS. 1 to 3. Therefore, in the embodiment in which the turret 1 turns around the B-axis, the invention described in the above item (1) can be implemented according to the above-described equations for the conversion.
(4) This invention also relates to a method of indicating an X-axis offset value (xcex94X) and a Z-axis offset value (xcex94Z) of a cutting edge 3 of a cutting tool in a control apparatus for a cutting machine having a turret 1 which can be turned to an arbitrary position, characterized in that the method includes the following steps;
a step of reading an X-axis value of the tool (L2) and a Z-axis value of the tool (L1) of the selected cutting tool 2, and reading an X-axis value of the turret (L4), and a Z-axis value of the turret (L3) stored in memory (S2).
a step of reading a turning angle (xcex1) of the turret 1 (S6).
a step of calculating the X-axis offset value (xcex94X) and the Z-axis offset value (xcex94Z) according to the following equations, employing the aforesaid X-axis value of the tool (L2), the Z-axis value of the tool (L1), the X-axis value of the turret (L4) and the Z-axis value of the turret (L3) (S7).
xcex94X=(xcex94Azxc2x7cos xcex1xe2x88x92xcex94Axxc2x7sin xcex1)xc3x972xe2x80x83xe2x80x83(Equation 1)
xcex94Ax=L2+L4
xcex94Az=L1+L3
xcex94Z=xe2x88x92xcex94Azxc2x7sin xcex1xe2x88x92xcex94Axxc2x7cos xcex1xe2x80x83xe2x80x83(Equation 2)
(xcex1: turning angle of the turret 1 relative to the B-axis. A vertically downward direction of the X-axis in FIG. 1 is set to be 0 degree)
a step of indicating the X-axis offset value (xcex94X) and the Z-axis offset value (xcex94Z) (S8).
In addition to indicating the offset values, the steps of conducting the cutting work further includes, as shown in FIG. 6, a step of exchanging the tool by an ATC (Automatic Tool Changer) (S4) after the step (S2), and a step of inputting the turning angle (xcex1) by the operator (S5) or a step of manually turning the turret 1 by the operator and reading the turning angle (xcex1) by a CPU prior to the step (S6).
(5) This invention also relates to a control apparatus for a cutting machine adapted to conduct numerical control and in which a cutting tool 2 can be rotated around the tool axis to an arbitrary position, characterized in that an X-axis value of the tool (L2r) of a cutting edge 3 when the cutting tool 2 has been rotated to an arbitrary angle is converted to a value on a coordinate relative to the cutting machine, and an X-axis offset value (xcex94Xr) after the rotation is obtained from the following equations employing this X-axis value of the tool (L2r) and an X-axis value of the turret (L4), whereby this X-axis offset value (xcex94Xr) is indicated.
xcex94Xr=xcex94Axrxc3x972
xcex94Axr=L2r+L4
In an embodiment in which the cutting tool 2 is simply rotated around the tool axis, an equation for conversion for xe2x80x9cconverting the X-axis value of the tool (L2r) of the cutting edge 3 after the rotation to the value on the coordinate relative to the cutting machinexe2x80x9d is L2r=L2xc2x7cos xcex2. In this manner, the operator can grasp the X-axis offset value, regardless of a rotation angle (xcex2) of the cutting tool 2, even in the case where the cutting tool 2 has been rotated around the tool axis to an arbitrary position, thus enabling a wear compensation value to be easily inputted.
(6) This invention also relates to a control apparatus for a cutting machine adapted to conduct numerical control and in which a cutting tool 2 can be rotated around the tool axis to an arbitrary position, characterized in that a Y-axis offset value of the tool (xcex94Y) of the cutting edge 3 when the cutting tool 2 has been rotated to an arbitrary angle is converted to a value on a coordinate relative to the cutting machine, and indicated. In a form in which the cutting tool 2 simply rotates around the tool axis, this Y-axis offset value (xcex94Y) can be obtained from an equation, xcex94Y=L2xc2x7sin xcex2.
In this manner, the operator can grasp the Y-axis offset value, regardless of a rotation angle (xcex2) of the cutting tool 2, even in case where the cutting tool 2 has been rotated around the tool axis to an arbitrary position, thereby to facilitate an input of a wear compensation value.
(7) Further, this invention relates to the above described control apparatus, characterized in that wear compensation values (xcex94Xt, xcex94Yt) are indicated in relation to the X-axis offset value (xcex94Xr) and the Y-axis offset value (xcex94Y) when the cutting tool 2 has been rotated to an arbitrary angle. Further, this control apparatus is preferably in such a form that the inputted wear compensation values (xcex94Xt, xcex94Yt) may be indicated in order of the input.
Accordingly, in the same manner as in the above item (2), this invention is able to provide the operator with guidelines for the wear compensation values. In addition, by providing means for indicating the inputted wear compensation values in order, the operator can see a history of the wear compensation values in the past, and can easily set the next wear compensation values.
One of desirable embodiments of this invention is an embodiment in which the Z-axis wear compensation value (xcex94Zt) is indicated in relation to the Z-axis offset value (xcex94Zr), and the inputted wear compensation value (xcex94Zt) is indicated in order of the input.
(8) This invention also relates to the control apparatus as described in the above items (1) to (3), characterized in that the cutting tool 2 can be rotated around the tool axis to an arbitrary position, the X-axis value of the tool (L2r) of the cutting edge 3 when the cutting tool 2 has been rotated to the rotation angle (xcex2) is obtained from L2r=L2xc2x7cos xcex2, and that the X-axis offset value and the Z-axis offset value when the turret 1 has been turned to the turning angle (xcex1) are calculated according to the following equations, and these X-axis offset value (xcex94Xr) and the Z-axis offset value (xcex94Zr) are indicated.
xcex94Xr=(xcex94Azxc2x7cos xcex1xe2x88x92xcex94Axrxc2x7sin xcex1)xc3x972xe2x80x83xe2x80x83(Equation 3)
xcex94Axr=L2+L4
xcex94Az=L1+L3
xcex94Zr=xe2x88x92xcex94Azxc2x7sin xcex1xe2x88x92xcex94Axrxc2x7cos xcex1xe2x80x83xe2x80x83(Equation 4)
According to this invention, even in the case where the cutting tool 2 rotates around the tool axis, and at the same time, the turret 1 turns, the X-axis offset value and the Z-axis offset value can be indicated as values on the coordinates relative to the cutting machine. As the results, the operator can make these X-axis offset value and Z-axis offset value as guidelines, thus facilitating the input of the wear compensation values on the X-axis and the Z-axis.